Arsenic in Mining Areas: Environmental Contamination Routes

Abstract

The emission and accumulation of toxic elements such as arsenic in various environmental compartments have become increasingly frequent primarily due to anthropogenic actions such as those observed in agricultural, industrial, and mining activities. An example of environmental arsenic contamination in Brazil exists in the city of Paracatu, MG, due to the operation of a gold mine. The aim of this work is to evaluate the routes and effects of arsenic contamination in environmental compartments (air, water, and soil) and environmental organisms (fish and vegetables) from mining regions as well as the trophic transfer of the element for a risk assessment of the population. In this study, high levels of arsenic were found in the waters of the Rico stream ranging from 4.05 µg/L during the summer season to 72.4 µg/L during the winter season. Moreover, the highest As concentration was 1.668 mg kg^-1 in soil samples, which are influenced by seasonal variation and by proximity to the gold mine. Inorganic and organic arsenic species were found above the allowed limit in biological samples, indicating the transfer of arsenic found in the environment and demonstrating a great risk to the population exposed to this area. This study demonstrates the importance of environmental monitoring to diagnose contamination and encourage the search for new interventions and risk assessments for the population.

Keywords: environmental monitoring; particulate matter; risk; toxic metal.

Figure 1

Map of the city of Paracatu, MG, with the points of water and soil sample collection. Software used is ArcGis version 10.8.

Figure 2

Results of the analysis of arsenic in water (A) and soil (B) at points P1, P2, P3, P4, and P5 of the Rico stream and atmosphere (C). Particulate matter up to 2.5 µm (PM 2.5) and particulate matter in total suspension (PTS) collected in the regions of Amoreiras (AM), Chapadinha (CH), and Paracatu (PA). Analyses were carried out in the winter of 2017 and summer of 2018. The limit (LM) is <10 µg L⁻¹ for surface water [36,41] and <15 mg kg⁻¹ for soil [42]; >35 mg kg⁻¹ requires agricultural intervention [43]. α < 0.05.

Figure 3

Average rainfall index (mm) and average maximum and minimum temperatures (°C) over the months from 1973 to 2018. Measurements obtained by the Brazilian National Institute of Meteorology.

Figure 4

Quantification of As species (As³⁺, As⁵⁺, MMA, and DMA) in samples of corn, cassava, and fish exposed to water and soil on the banks of the Rico stream. ∑As = sum of As species; LM = maximum limit of As (LM fish 1.0 mg kg⁻¹, LM corn 0.2 mg kg⁻¹, and LM cassava 0.1 mg kg⁻¹) [47].

Figure 5

Microscopic image of the mitosis subphases of meristematic cells from the root of Allium cepa: (a) interphase; (b) prophase; (c) metaphase; (d) anaphase; (e) telophase and chromosomal aberrations (CAs); (f) micronucleus interphase; (g) micronucleus prophase; (h) C-metaphase; (i) anaphase with chromosomal loss; and (j) telophase with bridge and break.

Figure 6

Occurrence of micronuclei in Allium cepa meristematic cells exposed to samples collected in the Rico stream (P1, P2, P3, P4, and P5) and negative control of ultrapure water (NC) for 24 h. Tukey test with significance level of q = 0.05.